This invention relates to a novel process for the oxidation of hydrocarbons. More particularly, this invention relates to the catalytic oxidation of a wide range of oxidizable hydrocarbons, particularly alkanes, with air or oxygen. The catalyst is a halogenated ligand complex of compounds containing one or more cations of iron.
The oxidation of alkanes and other aliphatic hydrocarbons catalyzed by transition metal complexes in the liquid phase is well known in the art, and commercial applications of this technology are extensive. See, for example, J. E. Lyons, Hydrocarbon Processing, November, 1980, 107, Table I.
However, the selective partial oxidation of unactivated hydrocarbons such as methane, ethane, propane, butanes and the like by air or oxygen as the oxidant is extremely difficult to achieve. The use of macrocyclic metal complexes such as metalloporphyrins as catalysts in the liquid phase has not been successful in giving rapid rates and high selectivities under mild conditions using air or oxgen as the oxidant. Some success has been achieved using two less economically desirable approaches:
(1) The use of metalloporphyrin catalysts such as Fe(TPP)Cl and Mn(TPP)Cl (where "TPP" is the dianion of 5, 10, 15, 20-tetraphenylporphine) with iodosylbenzene, sodium hypochlorite, alkylhydroperoxides or other expensive non-regenerable oxidants. [P. Traylor, D. Dolphin, and T. Traylor, J. Chem. Soc. Chem. Comm., 279 (1984); J. Groves, W. Kruper, Jr., and R. Haushalter, J. Am. Chem. Soc., 102, 6377 (1980); C. Hill, and B. Schardt, J. Am. Chem. Soc., 102, 6374 (1980); J. Smegal and C. Hill, J. Am. Chem. Soc., 105, 3515 (1983); A. Middleton and D. Smith, U.S. Pat. No. 4,459,427 (July 10, 1984)]; and
(2) The use of metalloporphyrin catalysts with molecular oxygen as oxidant and simultaneous addition of a reductant such as NaBH.sub.4, ascorbic acid or colloidal platinum with H.sub.2. Again, the added reagents are expensive and non-regenerable. Examples of this approach can be found in D. Mansuy, M. Fontecave, and J. Bartoli, J. Chem. Soc. Chem. Comm. 253 (1983); I, Tabushi and A. Yazaki, J. Am. Chem. Soc., 103, 7371 (1981).
It is, therefore, an object of this invention to provide an improved metal coordination complex-catalyzed process for the oxidation of hydrocarbons, and particularly alkanes, using air or oxygen, but without the need for added expensive, non-regenerable oxidants, reductants, or other co-catalysts.